The present invention relates to an analytical aid comprising a lancet and a test element, a method for producing such an analytical aid, and a method for analysing a sample using such an analytical aid.
In clinical diagnostics, examination of blood samples or of interstitial fluid permits early and reliable detection of pathological conditions and also specific and reliable monitoring of physical states. Medical diagnostics entails obtaining a sample of blood or of interstitial fluid from the individual who is to be examined.
To obtain the sample, the skin of the person to be examined can be punctured, for example at the finger pad or ear lobe, with the aid of a sterile, sharp lancet in order to obtain a small amount of blood or interstitial fluid for the analysis. This method is particularly suitable for sample analysis that is carried out directly after the sample has been obtained.
In the area of home monitoring in particular, i.e., where persons without specialized medical training carry out simple analyses of blood or of interstitial fluid themselves, and particularly for diabetics taking blood samples on a regular basis, several times a day, to monitor their blood glucose concentration, lancets and associated devices (puncturing aids) are sold that allow samples to be taken with the least possible discomfort and in a reproducible manner. Such lancets and devices (puncturing aids) are the subject matter of, for example, WO-A 98/48695, EP-A-0 656 970, U.S. Pat. Nos. 4,442,836 or 5,554,166.
Self-monitoring of blood glucose levels is a method of diabetes control that is now applied worldwide. Blood glucose monitors in the prior art typically include an analysis device (meter) into which a test element (test strip) is inserted. The test element is brought into contact with a droplet of a sample which has previously been obtained by means of a puncturing aid, for example from the pad of a finger. Analytical test elements of this kind are known from CA 2,311,496, for example. The analytical test element described there contains a detection element and a channel that permits capillary transport of fluid, so that when the test element comes into contact with a droplet of blood at the sample application site, blood is brought into contact with the detection element and a detectable reaction with the analyte takes place.
The numerous system components needed for self-monitoring of blood glucose (lancet, puncturing aid, test element and analysis device) take up a great amount of space and entail relatively complex handling. There are now also systems with a higher degree of integration and, consequently, easier handling, for example ones in which the test elements are stored in the analysis device and made available from this for the measurement. A next step in miniaturization may be achieved, for example, through the integration of several functions or functional elements in a single analytical aid (disposable). For example, the operating sequence can be greatly simplified by suitable combination of puncturing procedure and sensor-based analyte concentration detection on one test element.
U.S. publication no. 2003/0050573 has as its subject matter an analytical aid with lancet and test element. The lancet comprises a lancet needle with a tip, and a lancet body which completely surrounds the lancet needle at least in the area of the tip, the lancet needle being displaceable relative to the lancet body. At least in the area of the tip of the needle, the lancet body is made of an elastic material into which the lancet needle is embedded. The analytical test element is connected fixedly to the lancet body.
U.S. publication no. 2003/0211619 relates to bands with testers arranged thereon which each comprise a test strip sensor and a micro needle. The proximal end of each tester is secured on the band, so that the tester, when it is not sealed, can be bent away from the edge.
U.S. Pat. No. 4,648,408 concerns a blood-testing device made up of three plastic blocks which can be folded together and on which, in addition to a needle, there are also a reagent strip and a disinfectant.
U.S. publication no. 2002/0052618 A1 has as its subject matter an analytical aid with integrated lancet in a lancet body, the lancet body being connected movably, for example tiltably or pivotably, to a frame part of a test element, such that the lancet can adopt a storage position and a puncture position, the lancet in the storage position being substantially parallel to the plane of the test element and, in the puncture position, being substantially orthogonal to the plane of the test element.
U.S. publication no. 2004/0064068 A1 relates to a lancet arrangement integrated into a measurement strip. According to one embodiment described (FIG. 3), the angle between the movement of the lancet and the plane of the measurement surface of the measurement strip is variable.
U.S. publication no. 2003/0212347 A1 concerns devices comprising at least one skin-puncturing element, a biosensor, and a liquid transport path between the skin-puncturing element and the biosensor. According to one embodiment described (FIG. 8), such a device is designed in such a way that the skin-puncturing element (lancet) can be turned away from the plane of the biosensor about a pivot axis.
EP 1 508 304 A1 relates to a medical device having an upper and a lower flexible sheet, a lancet body and a test strip. The lancet body has an opening into which a puncture element extends. The reaction zone of the test strip is in contact with the opening in the lancet body. This has the disadvantage that some of the test chemicals present on the reaction zone can reach the puncture element and that sterilizing of the puncture element is not possible without undesired sterilizing of the reaction zone.
These analytical aids known from the prior art are complicated in structure, in most cases with a large volume, are impractical in use, and are expensive to produce.
A large number of problems have to be addressed in the production of analytical aids. The lancet has to be sterilized, and the sterile condition of the lancet has to be guaranteed for the period of use of the analytical aid. The function and action of the test chemicals present in the test field of the test element may be adversely affected by the known sterilization methods. Sensitive chemical or biological substances may be damaged. Therefore, the test chemicals should to the extent possible not be exposed to the sterilization method for the lancet. For use of the analytical aid, the sterile protection must also be able to be safely removed without risk of injury to the user.